This invention relates to the making of dental study models by casting of plaster in maxillary and mandibular impressions.
Dental study models are generally cast by plaster deposited into the base molding cavity of a model former facing the impression side of an impression holding tray into which plaster is also placed. The two masses of wet plaster are united as the tray is positioned by the dental mechanic over the plaster filled cavity in the former resulting in a unitary hardened plaster model that is exposed upon removal from the tray and model former. Upper and lower models that are occusally related by a previously prepared wax bite, when so cast require a substantial amount of plaster trimming because the base molding cavity is made large enough to accommodate expected variations in manual positioning of the impression trays relative to the model former during the casting operations. Furthermore, since the cavity is often oval shaped and large enough to cover many mouth sizes, a considerable amount of trimming is necessary.
It is therefore an important object of the present invention to provide a method and apparatus for substantially reducing the amount of model trimming heretofore required in connection with the making of dental study models.